绿盲蝽越冬卵的耐寒能力

近年来,随着转基因棉花的大面积推广,绿盲蝽成为了我国棉花和果树生产的重要害虫。为了阐明绿盲蝽越冬生态适应性,研究了绿盲蝽卵在越冬过程中的耐寒力变化,测定了卵内生化物质的含量,结果表明:绿盲蝽越冬卵低温存活力呈现出明显的月份变化,在-10℃、-20℃处理下,绿盲蝽的越冬卵的半致死时间从大到小的顺序依次为:1月>2月>12月>3月>4月,在-30℃处理下从大到小的顺序依次为:1月>12月>3月>2月>4月。在极端低温(-20℃)下1、2、3、4和5 d后,4月份保护卵死亡率明显低于相同处理下的4月份裸露卵的死亡率,枣枝中的越冬卵死亡率分别为4.32%、5.36%、5.42%、6.79%和7.63%,剥离出来的越冬卵死亡率分别为46.06%、51.84%、54.59%、63.07%和74.41%。人工滞育卵的耐寒性强于正常发育卵的耐寒性,弱于自然越冬过程中滞育卵的耐寒性。冷驯化可以显著提高绿盲蝽越冬卵的低温存活力,在0℃冷驯化20 min后,越冬卵的低温(-20℃、100 h)死亡率显著降低,冷驯化40 min后,低温死亡率趋于平稳,均在37%左右。越冬卵体内物质呈明显的季节性变化,越冬卵越冬期的含水量显著高于越冬后,其中1月份最高(43.98%),4月份达到最低(38.79%)。越冬卵体内总脂肪含量在整个越冬过程中逐渐降低,从12月份的38.24%,降低到4月份的27.08%。蛋白质和糖的含量均是先降低后升高,其中蛋白质从12月份的78.77μg/mg,降低到1月份的59.80μg/mg,然后又逐渐升高至4月份的73.62μg/mg,体内总糖含量由12月份的39.60μg/mg降低至1月份的21.17μg/mg,然后又逐渐升高至4月份的35.10μg/mg。绿盲蝽越冬卵的耐寒力随着月份的变化而变化,在整个越冬期间表现出较强的抗寒性,能够抵御冬季低温,而其越冬场所的保护作用增加了其对于冬季严寒的适应性。

Cold tolerance of the overwintering egg of Apolygus lucorum Meyer-Diir (Hemiptera: Miridae)

Apolygus lucorum has become one of the most pestiferous pests of cotton and fruits with widely applications of transgenic Bt cotton in China.Cold tolerance of its overwintering eggs was studied,and the content of biochemical substances was also determined,to evaluate its overwintering adaptability.The results showed that there were significant differences on cold survival ability of the overwintering eggs among months.Lt50 of the overwintering eggs was in order of January > February > December > March > April at the temperature of-10 ℃ or-20 ℃,and in order of January > December > March >February > April at the temperature of-30 ℃.The mortality of protected eggs in the April(4.32%,5.36%,5.42%,6.79% and 7.63%) was significantly lower than non-protected eggs in the April(46.06%,51.84%,54.59%,63.07% and 74.41%) when they were treated at the temperature of-20 ℃for 1,2,3,4 and 5 days.The cold tolerance to lower temperature of artificial diapause eggs was higher than the normal eggs,while lower than the diapause overwintering eggs.The cold acclimation increased the cold tolerance of overwintering eggs of A.lucorum.The mortality of overwintering eggs at the temperature of-20 ℃for 100 hours decreased significantly after the overwintering eggs was treated at 0 ℃ for 20 minutes,and the mortality was always about 37% at the temperature of-20 ℃for 100 hours after was treated at 0 ℃ for more than 40 minutes.The content of biochemical substances of overwintering eggs changed seasonally.The water content of overwintering eggs in winter was significantly higher than those after winter,and was highest in January(43.98%) and lowest in April(38.79%).The fat content of overwintering eggs decreased from 38.24% in December to 27.08% in April over the winter.The protein content and glycogen content all reduced at first,then increased.The protein content decreased from 78.77 μg/mg in December to 59.80 μg/mg in January,then increased gradually to 73.62 μg/mg in April.The glycogen content decreased from 39.60 μg/mg in December to 21.17 μg/mg in January,then increased gradually to 35.10 μg/mg in April.In conclusion,cold tolerance of overwintering eggs of A.lucorum changed seasonally.The overwintering eggs showed high tolerance to the low temperature in winter,and the protection of overwintering place improved its overwintering adaptability.